Automatic master paper exchange for a copying machine

ABSTRACT

In a copying machine of the type wherein a image from subject sheets is formed on a master paper and then the image on the master paper is transcribed onto a plain paper while the master paper rotates around a rotary drum with the revolution of the drum, the improvement which comprises a holder secured directly on the rotary drum for holding the master paper around the rotary drum together with means for swinging the holder about its one end at a predetermined position in the course of the drum revolution. Thus, the holder may be spaced away from the surface of the rotary drum by means of the swinging means to enable the withdrawal of the exhausted master paper from the rotary drum. At this time, a new master paper may be wound about the rotary drum.

United States Patent [191 Kato [ Nov. 18, 1975 1 AUTOMATIC MASTER PAPER EXCHANGE FOR A COPYING MACHINE [75] Inventor: Ituro Kato, Nara, Japan [73] Assignee: Sharp Kabushiki Kaisha, Osaka,

Japan [22] Filed: May 17, 1974 [21] Appl. No.: 470,792

[30] Foreign Application Priority Data Primary Examiner-John M. Horan Attorney, Agent, or FirmStewart and Kolasch, Ltd.

[57] ABSTRACT In a copying machine of the type wherein a image from subject sheets is formed on a master paper and then the image on the master paper is transcribed onto a plain paper while the master paper rotates around a rotary drum with the revolution of the drum, the improvement which comprises a holder secured directly on the rotary drum for holding the master paper around the rotary drum together with means for swinging the holder about its one end at a predetermined position in the course of the drum revolution. Thus, the holder may be spaced away from the surface of the rotary drum by means of the swinging means to enable the withdrawal of the exhausted master paper from the rotary drum. At this time, a new master paper may be wound about the rotary drum.

7 Claims, 3 Drawing Figures U .s. Patent 1-10v;18,1975 sheetlofz 3,920,327

FIG. I

U.S.-Patent Nov. 18,1975 Sheet 2vof2 3,920,327

FIG. 2

FIG. 3

embodying the present invention;

AUTOMATIC MASTER PAPER EXCHANGE FOR A COPYING MACHINE BACKGROUND OF THE INVENTION The present invention relates to a copying machine of the type wherein a master paper is wound around a rotary drum, and more particularly relates to a mechanism for exchanging the exhausted master paper held around the rotary drum for the new master paper.

As used herein, the term master paper refers to a sensitive paper for use in electrostatic printing machines or a subject sheet for use in offset presses.

The sensitive paper on the rotary drum in the electrostatic printing machines must be exchanged when it has become exhausted or damaged during repeated electrostatic printing processes. In the case where the sensitive paper is made from ZnO, it must be exchanged for the new one, for example, after about 400 sheets have been copied. Likewise, the subject sheet on the rotary drum in offset presses must be exchanged for a new one after the printing of the content has been completed.

The conventional method for exchanging the master paper relies upon manual labor. The exhausted master paper wound around the rotary'drum is removed manually therefrom and then a new master paper is manually wound about the rotary drum. This is very troublesome and may cause shear of the printing.

' OBJECTS AND SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a mechanism which can provide an automatic exchange of the master paper for use in copying machines. To achieve the above object, and pursuant to the present invention, a holder is provided on the rotary drum for holding the master paper around the rotary drum. Also, means are provided for swinging the holder about its one end when it is at a predetermined position so that the holder may be spaced away from the surface of the rotary drum to enable the withdrawal of the exhausted master paper from the rotary drum and the winding of the new master paper about the rotary drum.

BRIEF DESCRIPTION OF THE DRAWINGS tray 6 for receiving printed sheets and a paper cassette 7 for supplying plain papers for transcription. A master switch 8 and a master paper entrance 9 are provided for exchanging the master paper held around a rotary drum 10 (See FIGS. 2 and 3). The detail of the mechanism for exchanging the master paper will be explained later. Element 11 is a main switch.

Referring to FIGS. 2 and 3, the mechanism for exchanging the master paper is shown in a preferred arrangement. The rotary drum 10 carries a master paper and rotates in the counter-clockwise direction, as viewed in FIG. 3. A corona charging device 12, light shields 13 for exposure, a magnetic developer brush 14, another corona charging device 15 for transcription and afur brush 16 for cleaning the master paper are mounted at stations adjacent the periphery of the rotary drum 10 for the purpose of forming images on the master paper and transcribing the images onto plain papers.

A holder 17 is provided on the surface of the rotary drum 10 in a manner to hold the master paper around the rotary drum 10. The holder 17 is fixed to a shaft 18. A cam or dog 19 is fixed to one end of the shaft 18 for transferring the torque of the rotary drum 10 to a rotatable dog 20. The holder 17 and the plate 19 rotate in unison with the shaft 18. Springs 21 are provided at the both ends of the rotary drum 10 and connected to the rotary drum 10 and the holder 17 to force the pointed end of the holder 17 toward the surface of the rotary drum l0 and hold the leading edge of the master paper in order to wind the master paper around the rotary drum. The rotatable plate is rotatably mounted about a drum shaft 22 with a play. Projections 201 and 202 are provided at the periphery of the rotatable plate 20. The first and second projections of the rotatable plate 20 are usually placed at the bottom of the rotatable cam because of'their weight. The rotatable plate 20 begins to rotate in unison with the rotary drum 10 when the dog 19 contacts the projection first 2 01 in the F cource of the rotation of the rotary drum, and rotates FIG. 1 is a perspective view of a copying machine FIG. 2 is a partially sectional plan view showing the embodiment of the present invention; and

FIG. 3 is a side view of the embodiment of the present invention taken along the line lIl-lll of FIG. 2 as viewed in the direction of the appended arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a copying machine which carries out an electrostatic printing process. A subject cover 1 covers alone after the projections pass their top portion. A stopper 23 is introduced in order to prevent the rota- .tion of the rotatable plate, by energizing a solenoid 24 and pulling a plunger 25.

When the .stopper 23 is extended and the rotary drum 10 rotates, the rotatable plate 20 begins to rotate in unison with the rotary drum 10 until the dog 19 engages with the first'projection 201. The rotation of the rotatable plate 20 is inhibited when the second projection 202 reaches the position of the stopper 23. In this situation, the dog 19 moves to escape from the first projection 201 against the compression force of the springs 21, since the rotary drum 10 rotates continuously. The dog 19 returns to the normal state after passing the projection first 201 and at the same time the rotatable plate 20 rotates alone in the clockwise direction because of its weight. The rotatable plate 20 again begins to rotate in unison with the rotating drum 10 after the cam 19 engages with the second projection 202. The cam 19 repeats the swinging action when the second projection 202 again reaches the position of the stopper 23. The holder 17 swings about the shaft 18 as the cam 19 swings in the manner previously described, since the holder 17 and the dog 19 are both fixed to the shaft 18, and hence the point end of the holder 17 is spaced away from and then contacts the periphery surface of the rotary drum l0.

Master paper feeding rollers 26 and 27 rotate upon the depression of the master switch 8. When a change of the master paper is required, the master switch 8 is depressed and a new master paper is inserted through the master paper entrance 9. The inserted new master paper 28 is fed forward by the rollers 26, 27 and activates a microswitch 29 provided behind the rollers 26, 27. Signals from the microswitch 29 disconnect a clutch and hence the rollers 26, 27 stop rotating. At this time, the rotary drum 10 begins to rotate and the solenoid 24 is energized. When the holder 17 on the rotary drum 10 reaches the portion corresponding to the end of the inserted new master paper, the rollers 26, 27 begin to rotate again, and the new master paper 28 is wound around the rotary drum in a manner such that theend thereof is held by the holder 17. The time when the rollers 26, 27 begin to rotate again is determined by the detecting means (not shown) which detects the position of the holder 17 on the rotary drum 10.

The holder 17 is spaced away from the surface of the rotary drum 10 twice during a full revolution, since the two projections 201, 202 are provided on the rotatable plate 20. Exhausted master paper feeding out rollers 30, 31 and an air blow-off nozzle 32 are provided the position where the holder 17 swings at the first time for withdrawing the exhausted master paper 33 from the rotary drum. The new master paper 28 is held by the holder 17 at the second swing operation thereof and wound around the rotary drum 10. That is to say, the withdrawal of the exhausted master paper, and the supplying and winding of the new master paper are carried out automatically and at the same time.

In FIG. 3, rollers 34, 35, 36 and 37 and guides 38 are provided for feeding to the charging device the plain paper 39 on which the images on the master paper are transcribed.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications are intended'to be included within the scope of the following claims.

I claim:

1. An automatic master paper exchange apparatus for a copying machine of the type wherein a master paper repeatedly usable for the copying process rotates around a rotary drum with the revolution of the drum, which comprises a rotary drum, holding means operatively associated with the drum for gripping a leading edge of the master paper in order to wind the master paper around the rotary drum, a rotatable plate rotatably disposed about the shaft of the rotary drum, said rotatable plate being rotatable without regard to the rotation of the shaft, a dog for transferring the torque of the rotary drum to the rotatable plate, means for coupling the holding means with the dog in order to swing the holding means in unison with thedog, a stopper adapted to engage the rotatable plate which swings the dog to disengage from the rotatable plate thereby discontinuing the rotation of the rotatable plate and means for shifting the stopper to an operative position at a time when the exchange of the master paper is desired.

2. The automatic master paper exchange apparatus of claim 1, wherein the holding means and dog means are disposed at the periphery of the drum and the rotatable plate is provided with two projections provided at the periphery thereof, said projection being adapted to sequentially engage the cam which transfers the torque of the rotary drum to the rotatable plate which in turn causes the holding means to disengage from the surface of the drum for releasing the old master paper and accepting the new master paper.

3. The automatic master paper exchange apparatus for an electrostatic copying machine according to claim 2, wherein an electrostatic image is formed on the master paper and transferred to a plain paper.

4. The automatic master paper exchange apparatus of claim 2, wherein holding means is spring loaded.

5. The automatic master paper exchange apparatus of claim 2, wherein means are provided for introducing a new master paper to the surface of the drum, means are provided for removing the exhausted master paper from the surface of the drum and means are provided for introducing plain paper on which the images on the master paper are to be transferred, to and from the surface of the drum.

6. The automatic master paper exchange apparatus of claim 2, wherein the stopper means is operatively associated with a plunger and a solenoid.

7. The automatic master paper exchange apparatus for an electrostatic copying machine according to claim 2, wherein an electrostatic image is formed on the master paper and transferred to a plain paper and wherein the projections are in a spaced-apart relationship. 

1. An automatic master paper exchange apparatus for a copying machine of the type wherein a master paper repeatedly usable for the copying process rotates around a rotary drum with the revolution of the drum, which comprises a rotary drum, holding means operatively associated with the drum for gripping a leading edge of the master paper in order to wind the master paper around the rotary drum, a rotatable plate rotatably disposed about the shaft of the rotary drum, said rotatable plate being rotatable without regard to the rotation of the shaft, a dog for transferring the torque of the rotary drum to the rotatable plate, means for coupling the holding means with the dog in order to swing the holding means in unison with the dog, a stopper adapted to engage the rotatable plate which swings the dog to disengage from the rotatable plate thereby discontinuing the rotation of the rotatable plate and means for shifting the stopper to an operative position at a time when the exchange of the master paper is desired.
 2. The automatic master paper exchange apparatus of claim 1, wherein the holding means and dog means are disposed at the periphery of the drum and the rotatable plate is provided with two projections provided at the periphery thereof, said projection being adapted to sequentially engage the cam which transfers the torque of the rotary drum to the rotatable plate which in turn causes the holding means to disengage from the surface of the drum for releasing the old master paper and accepting the new master paper.
 3. The automatic master paper exchange apparatus for an electrostatic copying machine according to claim 2, wherein an electrostatic image is formed on the master paper and transferred to a plain paper.
 4. The automatic master paper exchange apparatus of claim 2, wherein holding means is spring loaded.
 5. The automatic master paper exchange apparatus of claim 2, wherein means are provided for introducing a new master paper to the surface of the drum, means are provided for removing tHe exhausted master paper from the surface of the drum and means are provided for introducing plain paper on which the images on the master paper are to be transferred, to and from the surface of the drum.
 6. The automatic master paper exchange apparatus of claim 2, wherein the stopper means is operatively associated with a plunger and a solenoid.
 7. The automatic master paper exchange apparatus for an electrostatic copying machine according to claim 2, wherein an electrostatic image is formed on the master paper and transferred to a plain paper and wherein the projections are in a spaced-apart relationship. 